Hepatocytes are an important target for the delivery of pharmacological agents. Greater efficacy and decreased toxicity would be gained by delivering these therapeutic agents, small and large, more selectively to hepatocytes. Our preliminary results describe the discovery of a new protein determinant, within the p17 protein of T7 phage that enables the highly efficient delivery of fusion proteins and phage particles to hepatocytes in mice in vivo. Our hypothesis is that this ligand is a promising ligand for delivery of both particulate and soluble agents into hepatocytes in vivo because it interacts with a hepatocyte-specific receptor. [unreadable] [unreadable]